Michel Pleimling

Virginia Polytechnic Institute and State University, Blacksburg, Virginia, United States

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Publications (110)161.79 Total impact

  • Ulrich Dobramysl, Michel Pleimling, Uwe C. Tauber
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    ABSTRACT: We study the pinning dynamics of magnetic flux (vortex) lines in a disordered type-II superconductor. Using numerical simulations of a directed elastic line model, we extract the pinning time distributions of vortex line segments. We compare different model implementations for the disorder in the surrounding medium: discrete, localized pinning potential wells that are either attractive and repulsive or purely attractive, and whose strengths are drawn from a Gaussian distribution; as well as continuous Gaussian random potential landscapes. We find that both schemes yield power law distributions in the pinned phase as predicted by extreme-event statistics, yet they differ significantly in their effective scaling exponents and their short-time behavior.
    05/2014;
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    Matthew T. Shimer, Uwe C. Tauber, Michel Pleimling
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    ABSTRACT: We employ Monte Carlo simulations to investigate the non-equilibrium relaxation properties of the two- and three-dimensional Coulomb glass with different long-range repulsive interactions. Specifically, we explore the aging scaling laws in the two-time density autocorrelation function. We find that in the time window and parameter range accessible to us, the scaling exponents are not universal, depending on the filling fraction and temperature: As either the temperature decreases or the filling fraction deviates more from half-filling, the exponents reflect markedly slower relaxation kinetics. In comparison with a repulsive Coulomb potential, appropriate for impurity states in strongly disordered semiconductors, we observe that for logarithmic interactions, the soft pseudo-gap in the density of states is considerably broader, and the dependence of the scaling exponents on external parameters is much weaker. The latter situation is relevant for flux creep in the disorder-dominated Bose glass phase of type-II superconductors subject to columnar pinning centers.
    Physical review. E, Statistical, nonlinear, and soft matter physics. 03/2014; 90(3-1).
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    Shahir Mowlaei, Ahmed Roman, Michel Pleimling
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    ABSTRACT: In order to model real ecological systems one has to consider many species that interact in complex ways. However, most of the recent theoretical studies have been restricted to few species systems with rather trivial interactions. The few studies dealing with larger number of species and/or more complex interaction schemes are mostly restricted to numerical explorations. In this paper we determine, starting from the deterministic mean-field rate equations, for large classes of systems the space of coexistence fixed points at which biodiversity is maximal. For systems with a single coexistence fixed point we derive complex Ginzburg-Landau equations that allow to describe space-time pattern realized in two space dimensions. For selected cases we compare the theoretical predictions with the pattern observed in numerical simulations.
    03/2014; 47(16).
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    Claude Godreche, Michel Pleimling
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    ABSTRACT: We consider the non-conserved dynamics of the Ising model on the two-dimensional square lattice, where each spin is influenced preferentially by its East and North neighbours. The single-spin flip rates are such that the stationary state is Gibbsian with respect to the usual ferromagnetic Ising Hamiltonian. We show the existence, in the paramagnetic phase, of a dynamical transition between two regimes of violation of the fluctuation-dissipation theorem in the nonequilibrium stationary state: a regime of weak violation where the stationary fluctuation-dissipation ratio is finite, when the asymmetry parameter is less than a threshold value, and a regime of strong violation where this ratio vanishes asymptotically above the threshold. The present study suggests that this novel kind of dynamical transition in nonequilibrium stationary states, already found for the directed Ising chain and the spherical model with asymmetric dynamics, might be quite general. In contrast with the later models, the equal-time correlation function for the two-dimensional directed Ising model depends on the asymmetry.
    Journal of Statistical Mechanics Theory and Experiment 01/2014; 2014(5). · 1.87 Impact Factor
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    Linjun Li, Michel Pleimling
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    ABSTRACT: Systems with a bulk first-order transition can display diverging correlation lengths close to a surface. This surface induced disordering yields a special type of surface criticality. Using extensive numerical simulations we study surface quantities in the two-dimensional Potts model with a large number of states $q$ which undergoes a discontinuous bulk transition. The surface critical exponents are thereby found to depend on the value of $q$, which is in contrast to prior claims that these exponents should be universal and independent of $q$. It follows that surface induced disordering at first-order transitions is characterized by exponents that depend on the details of the model.
    11/2013;
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    Ben Intoy, Michel Pleimling
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    ABSTRACT: When four species compete stochastically in a cyclic way, the formation of two teams of mutually neutral partners is observed. In this paper we study through numerical simulations the extinction processes that can take place in this system both in the well mixed case as well as on different types of lattices. The different routes to extinction are revealed by the probability distribution of the domination time, i.e. the time needed for one team to fully occupy the system. If swapping is allowed between neutral partners, then the probability distribution is dominated by very long-lived states where a few very large domains persist, each domain being occupied by a mix of individuals from species that form one of the teams. Many aspects of the possible extinction scenarios are lost when only considering averaged quantities as for example the mean domination time.
    Journal of Statistical Mechanics Theory and Experiment 07/2013; 2013(08). · 1.87 Impact Factor
  • Hyunhang Park, Michel Pleimling
    Physical Review Letters 06/2013; 110(23). · 7.73 Impact Factor
  • Ahmed Roman, Debanjan Dasgupta, Michel Pleimling
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    ABSTRACT: In order to better understand the interplay of partnership and competition in population dynamics, we study a family of generalized May-Leonard models with N species. These models have a very rich structure, characterized by different types of space-time patterns. Interesting partnership formations emerge following the maxim that “the enemy of my enemy is my friend”. In specific cases cyclic dominance within coarsening clusters yields a peculiar coarsening behavior with intriguing pattern formation. We classify the different types of dynamics through the analysis of the square of the adjacency matrix. The dependence of the population densities on emerging pattern and propagating wave fronts is elucidated through a Fourier analysis. Finally, after having identified collaborating teams, we study interface fluctuations where we initially populate different parts of the system with different teams.
    Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics 03/2013; 87(3).
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    Hyunhang Park, Michel Pleimling
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    ABSTRACT: Using numerical simulations we investigate the properties of the dynamic phase transition that is encountered in the three-dimensional Ising model subjected to a periodically oscillating magnetic field. The values of the critical exponents are determined through finite-size scaling. Our results show that the studied non-equilibrium phase transition belongs to the universality class of the equilibrium three-dimensional Ising model.
    Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics 03/2013; 87(3).
  • Hiba Assi, Ulrich Dobramysl, Michel Pleimling, Uwe Tauber
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    ABSTRACT: We investigate the non-equilibrium relaxation properties and steady states of interacting magnetic flux lines in type-II superconductors in the presence of driving external currents and / or different types and configurations of pinning centers. We model the vortices as elastic lines, and study the competing effects of thermal fluctuations, mutual repulsion, and pinning to defects. We employ both three-dimensional Monte Carlo and more efficient Langevin molecular dynamics simulations. Comparison of the resulting data for the non-equilibrium stationary states as well as the preceding relaxation regimes allows us to validate the utilization of both algorithms in out-of-equilibrium settings. We furthermore carefully analyze finite-size effects.
    03/2013;
  • Ahmed Roman, Debanjan Dasgupta, Michel Pleimling
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    ABSTRACT: Understanding why and how species co-exist is a necessary step to the program of manipulating multispecies environments in order to preserve the biodiversity of the environment of interest. To this end we consider a generalization of the cyclic competition of species model. We show that our model enjoys a Zn symmetry which is explained via a simple graph theoretic technique. This symmetry gives rise to pattern formation and cluster coarsening of the species. We show that biodiversity is achievable in the mean field limit provided that the species in the clusters have reaction rates which correspond to non-trivial equilibria.
    03/2013;
  • Ben Intoy, Sven Dorosz, Michel Pleimling
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    ABSTRACT: Although the mean-field solution for four species in cyclic competition is generally in good agreement with stochastic results, it fails to describe the extinction and absorbing states that finite size systems inevitably fall into. We study the effects of dimension, lattice type, and swapping rate between particles on the time it takes for the system to go into a static absorbing state, which consists of a neutral species pair. Lattice types discussed are the well mixed environment, the one-dimensional chain, the Sierpinski triangle, and the two-dimensional square lattice. Data presented were acquired with simulations that have around the order of a thousand lattice sites or less, to capture finite size effects. The formation of domains composed of neutral species yields long lived states which promote coexistence.
    03/2013;
  • Nick Borchers, Michel Pleimling, R. K. P. Zia
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    ABSTRACT: From complex biological systems to a simple simmering pot, thermodynamic systems held out of equilibrium are exceedingly common in nature. Despite this, a general theory to describe these types of phenomena remains elusive. In this talk, we explore a simple modification of the venerable Ising model in hopes of shedding some light on these issues. In both one and two dimensions, systems attached to two distinct heat reservoirs exhibit many of the hallmarks of phase transition. When such systems settle into a non-equilibrium steady-state they exhibit numerous interesting phenomena, including an unexpected ``freezing by heating.'' There are striking and surprising similarities between the behavior of these systems in one and two dimensions, but also intriguing differences. These phenomena will be explored and possible approaches to understanding the behavior will be suggested.
    03/2013;
  • Linjun Li, Michel Pleimling
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    ABSTRACT: Using extensive Monte Carlo simulations we study the properties of the non-equilibrium phase transition encountered in driven three-dimensional Potts systems with magnetic friction. Our system consists of two three-dimensional blocks, coupled through boundary spins, that move along their boundaries with a constant relative velocity. Changing the number of states in the system from two (Ising case) to nine states, we find different scenarios for the surface behavior depending on whether the bulk transition is continuous or discontinuous. In order to fully assess the properties of this non-equilibrium phase transition, we vary systematically the strength of the coupling between the two blocks as well as the value of the relative velocity. For strong couplings between the blocks the phase transition is found to be strongly anisotropic.
    03/2013;
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    Nickolas Gray, Djordje Minic, Michel Pleimling
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    ABSTRACT: In this article we review the relation between string theory and non-equilibrium physics based on our previously published work. First we explain why a theory of quantum gravity and non-equilibrium statistical physics should be related in the first place. Then we present the necessary background from the recent research in non-equilibrium physics. The review discusses the relationship of string theory and aging phenomena, as well as the connection between AdS/CFT correspondence and the Jarzynski identity. We also discuss the emergent symmetries in fully developed turbulence and the corresponding non-equilibrium stationary states. Finally we outline a larger picture regarding the relationship between non-perturbative quantum gravity and non-equilibrium statistical physics. This relationship can be understood as a natural generalization of the well-known Wilsonian relation between local quantum field theory and equilibrium statistical physics of critical phenomena. According to this picture the AdS/CFT duality is just an example of a more general connection between non-perturbative quantum gravity and non-equilibrium physics. In the appendix of this review we discuss a new kind of complementarity between thermodynamics and statistical physics which should be important in the context of black hole complementarity.
    International Journal of Modern Physics A 01/2013; 28(7). · 1.13 Impact Factor
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    Nasrin Afzal, Michel Pleimling
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    ABSTRACT: Recently, different numerical studies of coarsening in disordered systems have shown the existence of a crossover from an initial, transient, power-law domain growth to a slower, presumably logarithmic, growth. However, due to the very slow dynamics and the long-lasting transient regime, one is usually not able to fully enter the asymptotic regime when investigating the relaxation of these systems toward equilibrium. We here study two simple driven systems-the one-dimensional ABC model and a related domain model with simplified dynamics-that are known to exhibit anomalous slow relaxation where the asymptotic logarithmic growth regime is readily accessible. Studying two-times correlation and response functions, we focus on aging processes and dynamical scaling during logarithmic growth. Using the time-dependent growth length as the scaling variable, a simple aging picture emerges that is expected to also prevail in the asymptotic regime of disordered ferromagnets and spin glasses.
    Physical Review E 01/2013; 87(1-1):012114. · 2.31 Impact Factor
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    ABSTRACT: We employ an elastic line model to investigate the steady-state properties and non-equilibrium relaxation kinetics of magnetic vortex lines in disordered type-II superconductors using Langevin molecular dynamics (LMD). We extract the dependence of the mean vortex line velocity and gyration radius as well as the mean-square displacement in the steady state on the driving current, and measure the vortex density and height autocorrelations in the aging regime. We study samples with either randomly distributed point-like or columnar attractive pinning centers, which allows us to distinguish the complex relaxation features of interacting flux lines subject to extended vs. uncorrelated disorder. Additionally, we find that our new LMD findings match earlier Monte Carlo (MC) simulation data well, verifying that these two microscopically quite distinct simulation methods lead to macroscopically very similar results for non-equilibrium vortex matter.
    Physics of Condensed Matter 11/2012; 86(5). · 1.28 Impact Factor
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    Matteo Marcuzzi, Andrea Gambassi, Michel Pleimling
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    ABSTRACT: Symmetries represent a fundamental constraint for physical systems and relevant new phenomena often emerge as a consequence of their breaking. An important example is provided by space- and time-translational invariance in statistical systems, which hold at a coarse-grained scale in equilibrium and are broken by spatial and temporal boundaries, the former being implemented by surfaces - unavoidable in real samples - the latter by some initial condition for the dynamics which causes a non-equilibrium evolution. While the separate effects of these two boundaries are well understood, we demonstrate here that additional, unexpected features arise upon approaching the effective edge formed by their intersection. For this purpose, we focus on the classical semi-infinite Ising model with spin-flip dynamics evolving out of equilibrium at its critical point. Considering both subcritical and critical values of the coupling among surface spins, we present numerical evidence of a scaling regime with universal features which emerges upon approaching the spatio-temporal edge and we rationalise these findings within a field-theoretical approach.
    EPL (Europhysics Letters) 10/2012; 100(4). · 2.26 Impact Factor
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    Hyunhang Park, Michel Pleimling
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    ABSTRACT: In order to elucidate the role of surfaces at nonequilibrium phase transitions, we consider kinetic Ising models with surfaces subjected to a periodic oscillating magnetic field. Whereas, the corresponding bulk system undergoes a continuous nonequilibrium phase transition characterized by the exponents of the equilibrium Ising model, we find that the nonequilibrium surface exponents do not coincide with those of the equilibrium critical surface. In addition, in three space dimensions, the surface phase diagram of the nonequilibrium system differs markedly from that of the equilibrium system.
    Physical Review Letters 10/2012; 109(17):175703. · 7.73 Impact Factor
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    Hyunhang Park, Michel Pleimling
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    ABSTRACT: Using extensive Monte Carlo simulations we study aging properties of two disordered systems quenched below their critical point, namely the two-dimensional random-bond Ising model and the three-dimensional Edwards-Anderson Ising spin glass with a bimodal distribution of the coupling constants. We study the two-times autocorrelation and space-time correlation functions and show that in both systems a simple aging scenario prevails in terms of the scaling variable $L(t)/L(s)$, where $L$ is the time-dependent correlation length, whereas $s$ is the waiting time and $t$ is the observation time. The investigation of the space-time correlation function for the random-bond Ising model allows us to address some issues related to superuniversality.
    Physics of Condensed Matter 07/2012; 85(9). · 1.28 Impact Factor

Publication Stats

950 Citations
161.79 Total Impact Points

Institutions

  • 1970–2014
    • Virginia Polytechnic Institute and State University
      • Department of Physics
      Blacksburg, Virginia, United States
  • 2012
    • University of Lorraine
      • P2M - Physique de la Matière et des Matériaux
      Nancy, Lorraine, France
  • 2011
    • University of Luxembourg
      • Theory of Soft Condensed Matter Physics
      Letzeburg, Luxembourg, Luxembourg
    • Clarkson University
      • Department of Physics
      Potsdam, NY, United States
  • 2009
    • National Institute for Theoretical Physics
      Stellenbosch, Western Cape, South Africa
  • 2000–2007
    • Friedrich-Alexander Universität Erlangen-Nürnberg
      • Institute of Theoretical Physics
      Erlangen, Bavaria, Germany
  • 2006
    • Bielefeld University
      • Faculty of Physics
      Bielefeld, North Rhine-Westphalia, Germany
    • University of Florence
      Florens, Tuscany, Italy